Microwave induced KOH activation of guava peel carbon as an adsorbent for congo red dye removal from aqueous phase

The adsorption capacity of activated carbon prepared from guava fruit peel waste has been studied for congo dye. The activation process is carried out under microwave radiations in the presence of KOH. The guava peel based activated carbon (GPAC) and unactivated carbon (GPUC) have been characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. The comparative adsorption behavior of GPAC, GPUC and commercially activated carbon (CAC) has been studied for the congo red dye removal using batch adsorption experiments. The non-linear Langmuir and Frendulich isotherm models are used to stimulate the equilibrium data. The equilibrium data is represented by the Langmuir isotherm model. The kinetic model shows that pseudo second order kinetics has best fit to the experimental data (R 2 >0.90). Thermodynamic studies conclude that adsorption process is spontaneous and endothermic in nature. GPAC has emerged as efficient adsorbent for congo dye as compared to GPUC and CAC. Further, desorption studies show that 35.74 % of metal ions can be recovered by desorption in first cycle and adsorbent can be reused.